This invention relates generally to modular spacecraft configurations and, more particularly, to modular spacecraft electronic equipment panels that can be externally mounted on a core spacecraft structure.
Conventional spacecraft designs have placed electronic equipment units on panels located inside box-like equipment compartments, with the panels typically forming the walls of the compartments. The equipment compartments are an integral part of the spacecraft structure. Complex interconnecting wiring connects the different electronic units together. Heat dissipated from the electronics equipment is conducted into the compartment panels and radiates into space. The size of each compartment is determined in part by the heat radiating area needed to cool the equipment, so there is often unused volume within each compartment. Because only one side of the equipment panel is used as a radiator, the equipment compartments often have to be very large to maintain desired operating temperatures. A related problem is that accessing equipment requires the removal of panels from the equipment compartment. Not only are compartments of this type bulky to accommodate in a launch vehicle and difficult to access for servicing, but they typically need to be coupled to other thermal radiator panels, through heat-conducting pipes, to provide overall thermal management of the spacecraft.
Further, because the equipment compartments are integral with the core structure of the spacecraft, thermally induced stresses are a significant problem because of temperature differences between the modules and the spacecraft core structure. In brief, these conventional equipment compartments are structurally and thermally dependent on the spacecraft core structure, and the overall design of the spacecraft must take into account the thermal requirements of each module and the structural forces resulting from the presence of each module.
As a result of these difficulties, the spacecraft core structure is usually constructed to have a relatively high weight and volume, to support the modules and to provide an adequate thermal radiation area. Also, it is usually the case that the choice of materials of both the modules and the spacecraft core structure is limited because there is a concern for differential thermal expansion. A further difficulty is that removal or addition of an electronics equipment unit upsets the overall structural and thermal design to some degree. Alignment problems, thermal management problems, or both, can result from simply removing or adding a unit
All of the foregoing problems are attributable to interdependence of the equipment modules and the spacecraft core structure, which together interact, both structurally and thermally, as parts of a larger assembly. It will be appreciated, therefore, that there is a need for a different approach to the construction of spacecraft modules for supporting electronic equipment, to overcome the difficulties noted above. U.S. Pat. Ser. 5,897,080 filed DEC. 20, 1996, entitled "Externally Mountable Spacecraft Equipment Module," and assigned to the same assignee as the present application, discloses a spacecraft architecture in which modules in the form of base panels to which electronic components are attached, are designed to be structurally and thermally independent of a spacecraft core structure to which the modules are attached. The prior application is hereby incorporated by reference into the present application, which discloses and claims improved techniques for assembly and disassembly of modules of the type disclosed in the prior application.